Evaluation of the nutritive value of whole cassava plant as replacement for maize in
the starter diets for broiler chicken

E O Akinfala, A O Aderibigbe and O
Matanmi

Department of Animal Science
ObafemiAwolowoUniversity

,

Abstract

A four-week feeding trail was conducted with 153
one-week old hybro strain of broiler chicks to determine the replacement value of
sun-dried whole cassava plant meal (WCP) for
maize. A control diet, which contained 50%
maize as the major energy source was compared with two other diets, in which 25 and 50% of
the maize content was replaced with sun-dried whole cassava plant meal (12 5 and 25% WCP
in the diet). The whole cassava plant (WCP)
used in these replacements had a ratio (DM basis) of 2.5:1 of tuber to leaves and tender
stems, while the ratio of leaves to tender stems was 5:1.

There were no health problems in the chickens fed even
the highest level of whole cassava plant meal, and even though growth rates and feed
conversion were impaired (by 13 and 19% for
growth and 14 and 26% for feed conversion, on the 12 5 and 25% cassava plant meal diets,
respectively), the use of the whole cassava plant to replace maize could be economical in
situations where this feed resource was available at competitive prices.

Key words:Broilers, cassava, chickens, nutritive value, starter diets

Introduction

The cost of feeding has been put at 60-80% of the total cost of
production for intensively reared livestock especially poultry (Fajimi et al 1993; Tewe 1997). Maize is the chief source of energy in diets
for monogastric animals in Nigeria, where it may constitute up to 60% ofthe ration. The
increasing pressure on the use of maize by the human population and livestock feed
companies has resulted in an escalating price of maize in Nigeria in recent years. The use of cassava, a multi-purpose plant which
grows everywhere in the tropics, as a replacement for maize, could help to reduce the cost
of production and alleviate the problem of direct competition between livestock and humans
for maize (Tewe 1997; Akinfala 2000).

The available literature reports the use of either cassava root or
cassava leaf meal in poultry diets (Ravindran et
al 1986; Tewe and Egbunike 1992; Khajarern and Khajarern 1991; Aderemi et
al 2000). There is, however, a paucity
of information on the use of the whole cassava plant in the diets of poultry.

The objective of this study, therefore, was to evaluate the potential
of the whole cassava plant as replacement for maize in the diets of broiler chickens
during the starter phase.

Materials and Methods

Preparation of Whole Cassava Plant Meal

Fresh cassava tubers, leaves and tender stems of varying maturity
were collected after harvesting at a farm near the Obafemi Awolowo University Teaching and
Research Farm, Ile-Ife. The cassava tubers
were washed and sliced into pieces. The tender
stems were chopped with the aid of a cutlass. The
tubers, leaves and tender stems were sun-dried on concrete floors for about 7to 10 days
with daily turning, depending on the intensity of the sunlight. They were then milled using a grinding machine.
Whole cassava plant meal was prepared, which had the ratio of 2.5:1 of tuber to leaves and
tender stems while the ratio of leaves to tender stems was 5:1 These combinations were made so as to produce a
replacement for maize in terms of crude protein level (Table 1).

Preparation of Diets

A basal diet of 22% crude protein was formulated with 50% of maize. The maize was then replaced with the whole cassava
plant meal at rates of 25 and 50% to give 12.5 and 25%of whole cassava plant meal in the two WCP experimental diets (Tables 1 and 2).

Experimental Animals

A total of 153, one-week-old, broiler chicks (hybro strain) were
randomly allotted to the 3 experimental diets. They
were further subdivided on a weight basis to three subgroups thus making 3 replicates each
of 17 birds per treatment / replicate. They were housed in deep litter pens. Drinkers were washed daily and fresh feed and water
were served daily ad libitum for a period of four weeks The
litter was changed fortnightly and the vaccination and medication schedule were strictly
adhered to.Records of performance and economic
of production were kept on a weekly basis.

Chemical and Statistical Analysis

The proximate composition of the test ingredients, the whole cassava
plant, and the experimental diets was determined using the methods outlined by AOAC
(1995). Analysis of variance was carried out
on the performance data using the statistical software package of SAS (1988).

Results

Proximate composition of diets and test
ingredients

The diets had a similar
proximate analysis with only slightly higher levels of crude fibre as the proportion of
whole cassava plant was increased (Table 2).

Performance Characteristics

The growth rate decreased and feed conversion deteriorated as the
proportion of the whole cassava plant in the diet was increased (Table 3).

Table
3:Effect of replacing maize with whole
plant cassava meal

0
WCP

12 5
WCP

25
WCP

SEM

Body weight, g

Initial

96.8

100

95.4

2.1

Final

1106a

981b

910b

81

Daily gain

36.0a

31.4b

29.1b

2.9

DM intake, g/day

452

448

460

4.8

Feed conversion (DM/gain)

1.79a

2.04ab

2.26b

0.19

ab Means in the same row having
different superscripts differat p=0 05

Discussion

The primary aim of incorporating the whole cassava plant meal in the
diet was to serve as a replacement for maize. In
terms of proximate composition this was achieved (Table 2); however, the nutrients in the
whole cassava plant were apparently used less efficiently for growth than the nutrients in
maize. The proportions of the protein coming
from the different components of the whole cassava plant were calculated to be: 53, 6 and
40% for the leaf, tender stem and root fractions, respectively. It is therefore likely that on balance the protein
provided by the whole cassava plant was of rather
inferior quality compared with that from the maize In this connection,the amino acid
profile of the protein in the cassava leaf is rich in lysine (Khajaren et al 1977;
Devendra 1977; Smith 1992), while the protein in maize is poor in this amino acid However, the root contributed almost 50% of the protein
from the whole cassava plant, and it is well known that this protein is of poor quality as
compared to that contained in the leaves (Gómez and Noma 1986).

The cyanogenic glucosides present in cassava should not have been a
problem as sun-drying is known to reduce the level of these compounds to the point where
they have no negative effect on the animal (Tewe 1991; IITA 1994). Synthetic DL-methionine was also included in
the diet and this amino acid can help to detoxify the HCN, through its transformation to
the moreinnocuous thiocyanate (Tewe and Egbunike 1992; Tewe 1994). Finally, most of the varieties grown in the area
where this study was conducted were the sweet varieties, which have been reported to
contain low levels of cyanogenic glucosides (Tewe 1991).

There were no health problems in the chickens fed even the highest
level of whole cassava plant meal, and even though growth rates and feed conversion were
impaired (by 13 and 19% for growth and 14 and 26% for feed conversion, on the 12.5
and 25% cassava plant meal diets, respectively), the use of the whole cassava plant to
replace maize could be economical in situations where this feed resource was available at
prices competitive with maize. Thus, Wright
(1994) considered that a cassava-based diet would be competitive if the price of dried
cassava roots was less than 75% of the price of maize. In
certain rural areas of Nigeria, for example, the price for cassava root meal has been
reported to be only one quarter of the price of maize (Aderemi et al 2000).

Conclusions

The results of this study show that sun-dried whole cassava plant
meal can be incorporated into the starter diet of broiler chicks to replace 25 and 50%,
respectively of the maize (equivalent to 12.5 and 25% of the total diet), with no health
problems but at a cost of 13 to 14% reduction in growth rate and 19 to 26% poorer feed
conversion.

Acknowledgement

We wish to acknowledge the important contribution of Miss Kalejaiye
Funmi, Miss Ibiefo Blessing and Mr Adeyemo
Muyiwa during the course of this study.